PHP errors and warnings – WPLMS 3.6 & 3.7

Hi, I have a staging site where I installed WPLMS 3.6 and now 3.7. I keep having a few PHP errors on Free courses. I saved permalinks, no caching, disabled ALL plugins but WPLMS ones, went to default WPLMS (no child theme with custom functions etc.) tested under PHP 7.0, 7.1 and 7.2 but these issues remain: Error #1 - Logged-in user lands on a free course intro page for 1st time. (gone after refresh) Screenshot. Error #2 - Logged-in user clicks on Take this course (only happens once - once user enrolled he can access it next time without this error). Screenshot. Error #3 - Only in PHP 7.2 - Front-end course admin tab (error gone when putting cursor on search bar and click else where). Screenshot. Can yo have a look please? Note: I've disabled my production set-up for these tests (to be sure it wasn't faulty), but ultimately, if you re-activate my child theme and following plugins: I use WC Memberships that grants access to all non-free courses, using your "WPLMS with WC Memberships" plugin + a custom function.php snippet in child theme to make it compatible with WPML as well as redirecting take this course button to my pricing page. Thanks for your help!